The ion transporting properties of ionophorous antibiotics not been studied systematically, in particular the transporting ion selectivities of such antibiotics have not been measured quantitatively. The experiments of solvent extraction, zero current membrane conductance and potential recently carried out in many laboratories mainly concern the equilibrium properties of interactions between antibiotics and ions. It is clear from the thermodynamic point of view that the equilibrium properties can tell nothing about transport properties. My objective is to understand the selective ion (in particular cation) transport induced by ionophorous antibiotics across a model membrane in terms of a simple kinetic interpretation. In a series of three papers I have presented such a theoretical interpretation. The essence of the theory is defining an adaptability coefficient for each ion with respect to each antibiotics. When the number of antibiotics is much smaller than the number of ions, the ration of the adaptability coefficients can be regarded as the transporting ion selectivity. The equations of ion transport across a membrane can be constructed accordingly. To explore the ion transport properties of the antibiotics and to test the theory, I propose to do a series of experiments by using the idea of Ashton and Steinrauf (1970), namely using a lipid barrier to represent a membrane. A U-tube whose bottom filled with lipid (in which antibiotics are dissolved) separating the ionic solutions in two side arms can be used as a model membrane system for lipids denser than water. A W-tube is constructed for lipids lighter than water. Ions are then transported across the lipid barrier by the antibiotic carriers. The changes of cation concentration in the aqueous solutions can be measured by an atomic absorption/flame spectrometer of a pH meter. I plan to measure the adaptability coefficents and test the transport equations for each antibiotics. Since the value of adaptability coefficients could be dependent on the dielectric constant of the organic solvent, solvent of dielectric constant varying from 2 to 10 will be used. The possibility of transporting of transporting divalent ions will also be examined.